The present invention pertains to a material supply and discharge apparatus. More particularly, the present invention relates to a material supply and discharge apparatus having incorporated therein a hopper for temporarily holding a upwardly supplied material, and then, discharging the material from a downward discharge port.
A packaging system for automatically packing a variety of materials in bags in a predetermined weight incorporates a combination weighing device for weighing separate materials sequentially supplied from the outside in combination.
FIG. 9A is a schematic cross section showing a configuration of this combination weighing device.
That is, a funnel 3 for collecting separate materials 2 such as confectionery or caramel, for example, supplied from the outside is arranged upwardly of a reverse cone shaped frame 1.
Materials 2 collected by this funnel 3 are dispersed in a radiation manner by means of a dispersion feeder 4 provided at the lower part of the funnel 3. The thus dispersed materials are then supplied to stock hoppers 6 (only two hoppers shown) arranged along the peripheral face of the reverse cone shaped frame 1 by means of a plurality of forwarding feeders 5 arranged in a radiation manner on the frame 1.
The materials 2 supplied to stock hoppers 6 are temporarily held on these stock hoppers 6. Then, as shown in FIG. 9B described later, a shutter 10 provided at the bottom of each of these stock hoppers 6 is released, whereby the supplied materials are moved to a plurality of weighing hoppers 7 (only two hoppers shown) provided downwardly of each of the stock hoppers 6.
The weight of each of the materials 2 moved to these weighing hoppers 7 is weighed for each of weighing hoppers 7.
That is, the weight of each of the materials 2 carried inside of a respective one of a plurality of weighing hoppers 7 is weighed by a respective one of the plurality of weighing hoppers 7 arranged along the peripheral face of the reverse cone shaped frame 1.
Thereafter, there are selected each of the weighing hoppers 7 housing the materials 2 each of which a total of weight values obtained by combining the weight values of the materials 2 for the weighing hoppers 7 each coincides with a predetermined weight value or is within the range of a predetermined tolerance.
As shown in FIG. 9B described later, the shutters 10 each provided at the bottom of each of the selected weighing hoppers 7 are released, whereby the materials 2 each are guided to a collection shoot 8 provided downwardly of each of the weighing hoppers 7.
Therefore, a bag (not shown) is placed downwardly of this collection shoot 8, whereby the materials 2 are housed in that bag by the predetermined weight value, and are automatically packed.
FIG. 9B is a schematic cross section of each of the stock hoppers 6 and each of the weighing hoppers 7.
The stock hoppers 6 each and the weighing hoppers 7 each have a receptacle port 9 for the materials 2 at the upper end, and have a discharge port 11 for the materials formed at the lower end.
The previously described shutter 10 for opening and closing the discharge port 11 is mounted on a shaft 12 provided at one end of this discharge port 11.
A shaft of a stepping motor 13, for example, is linked with this shaft 12.
This stepping motor 13 is driven, whereby the shutter 10 is turned, and the discharge port 11 is controlled to be opened and closed.
Here, the stepping motor 13 rotates the shaft 12 by an angle according to the number of pulses for a pulse driving current applied to an energizing coil.
Therefore, the number of pulses for the driving current applied to this stepping motor 13 is controlled, whereby a rotation angle of the shaft of the stepping motor 13, i.e., an opening of the shutter 10 can be arbitrarily set.
In order to improve the operation response performance of the shutter 10, it is desirable to use the stepping motor 13 rather than a general direct current motor or inductive motor.
However, in a combination weighing device configured as shown in FIGS. 9A and 9B as well, the following problems remain unsolved.
That is, this combination weighing device is not executed by sliding a shutter opening and closing operation in order to ensure high response characteristics in shutter opening and closing operation. As shown in FIG. 9B, the weighing device is executed by fixing one end of the shutter 10 to the shaft 12, and then, rotating this shaft 12 by means of the stepping motor 13.
In a state in which materials 2 are housed in each of the stock hoppers 6 or each of the weighing hoppers 7, the load in the gravity direction of the materials 2 is applied to the shutter 10.
In the case where the shutter 10 is of slide type, the load in this gravity direction is subjected to a shutter holding mechanism, for example, a slide groove.
Hence, as shown in FIG. 9B, in a system for the shutter 10 to turn around the shaft 12, while the shutter 10 is closed, a hold current is fed to the stepping motor 13 linked with the shaft 12, thereby making it necessary to prevent the shutter 10 from turning when the load in the gravity direction of the materials 2 is applied.
In the meantime, while the shutter 10 is closed, it is general that the materials 2 are charged (dropped) intensively within a short period of time instead of being charged (dropped) continuously.
Therefore, the load in the gravity direction is not uniformly applied to the shutter 10 while the shutter 10 is closed. The load value is greater than the weight of the materials 2 by a shock applied while the materials are charged for a short period of time.
In order to prevent the shutter 10 from being opened due to this shock applied when the materials 2 are charged, it is required to set a hold current relevant to the stepping motor 13 to a hold current value such that the stepping motor 13 can apply to the shutter 10 a torque sufficient to bear the shock when the materials 2 are charged.
In this case, as described above, the materials 2 relevant to all the periods in which the shutters 10 in each of the stock hoppers 6 and each of the weighing hoppers 7 are closed are charged intensively within a short period of time.
Therefore, feeding a hold current bearing the shock when the materials 2 are charged to the stepping motor 13 all over the period when the shutters 10 are closed, including a period after the materials have been charged, causes wasteful power consumption.
In particular, in a combination weighing device as shown in FIG. 9A, there are provided a number of stock hoppers 6 and a number of weighing hoppers 7 arranged along the peripheral face of the reverse cone shaped frame 1. Thus, there occurs a problem that power consumption of the entire device increases, and the running cost of the combination weighing device increases.
When the shutter 10 is closed, the shutter 10 is suspended by a spring or the like against the load in the gravity direction of the materials 2, whereby the hold current relevant to the stepping motor 13 can be eliminated.
However, this spring is always connected. Therefore, in the case of opening the shutter 10, it is required to feed to the stepping motor an energizing current sufficient to overcome the biasing force of this spring, which causes wasteful power consumption.
The present invention has been made in order to solve the foregoing problem. It is an object of the present invention to provide a material supply and discharge apparatus for changing a hold current relevant to a motor in a state in which a hopper shutter is closed according to a material charge period and the subsequent period, thereby making it possible to restrain power consumption and reduce running cost while maintaining excellent shutter characteristics.
According to a first aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus comprising:
a hopper (6a, 7a) having a receptacle port for materials at an upper end thereof and a discharge port for the materials at a lower end thereof;
a material supply mechanism (4, 5, 6a) disposed upwardly of the hopper, the mechanism causing the materials to be dropped from the reception port into the hopper;
shutter (10) turnably mounted so as to open and close the discharge port relevant to the hopper, the shutter being driven to be opened and closed so as to be released downwardly under a load in the gravity direction of the materials when the materials are dropped from the material supply mechanism after the discharge port has been closed in order to temporarily hold the materials in the hopper;
a motor (17a, 17b) linked with the shutter in order to drive the shutter to be opened and closed, a holding current being applied during closing of the shutter, thereby the shutter imparting to the shutter a torque against a force released downwardly by the load in the gravity direction of the materials; and
a shutter control portion (19a) for setting the hold current applied to the motor from the start time for loading applied to the shutter caused by the materials dropped from the material supply mechanism to a predetermined period, to a first hold current value capable of applying to the shutter a torque bearing a shock when the materials are charged, and setting a hold current applied to the motor from after an elapse of the predetermined period to the start of discharge from a discharge port of the hopper to a second hold current value smaller than the first hold current value capable of applying to the shutter a toque against a force released downwardly under a load in the gravity direction of the materials.
In the material supply and discharge apparatus configured according to the first aspect, while the shutter of the hopper is closed, at the start of loading applied to the shutter when materials are started to be charged (dropped) into the hopper from the material supply mechanism, a high hold current sufficient to bear the shock is fed to the motor. However, after the start time for material charge (drop) into the hopper has elapsed, the hold current relevant to the motor may be smaller than a hold current when charging (dropping) is started. Therefore, power consumption caused by a hold current in a period when the hopper shutter is closed can be restrained.
According to a second aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the first aspect, wherein the shutter control portion (19a) comprises a motor control portion (20) for controlling the holding current so that an average current value of the hold current applied to the motor is reduced until the materials has been started to be discharged from the hopper discharge port after the materials have been received by the hopper as compared with the hold current value relevant to the motor at the start of loading relevant to the shutter caused by the materials dropped from the material supply mechanism.
In the material supply and discharge apparatus configured according to the second aspect, as in the first aspect, while the shutter of the hopper is closed, at the start of loading relevant to the shutter caused by the materials being started to be charged (dropped) into the hopper from the material supply mechanism, a high hold current sufficient to bear the shock is fed to the motor. However, after the start time for material charge (drop) into the hopper has elapsed, a motor hold current may be smaller than a hold current when charging (dropping) starts. Therefore, power consumption caused by a hold current in a period when the hopper shutter is closed can be restrained.
According to a third aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the first aspect, further comprising hold current adjusting means (29, 30) for adjusting a relationship between the first hold current value and second hold current value relevant to the motor at the start of the loading according to physical attributes of materials supplied into the hopper from the material supply mechanism.
According to a fourth aspect of the present invention, there is provided a material supply and discharge apparatus according to the second aspect, further comprising hold current adjusting means (29, 30) for adjusting a relationship between the first hold current value relevant to the motor at the start of the loading and the average current value according to physical attributes of materials supplied into the hopper from the material supply mechanism.
In the material supply and discharge apparatus configure according to the third and fourth aspects, a relationship between a hold current value when loading starts and an average current value is adjusted according to physical attributes such as weight per material to be charged (dropped) into a hopper, a total weight, or shape.
That is, according to the material supply and discharge apparatus configured according to the third and fourth aspects, the shock greatly varies depending on the physical attributes of the materials. Thus, the hold current value when the most efficient loading starts can be selected.
According to a fifth aspect of the present invention, there is provided a material supply and discharge apparatus according to the third aspect, wherein the hold current adjusting means (29, 30) comprises a hold current condition setting table (29) and a current adjuster circuit (30), wherein the first hold current value and a period of applying the first hold current and the second hold current value and a period of applying the second hold current or the like are stored for each of types of the materials in the hold current condition setting table, and the types of materials primarily include physical attributes of materials such as the weight, shape, and specific gravity of each material or a total weight of materials to be housed one time in one hopper, the physical attributes being a milestone of a shock during material drop or a static weight after dropped; wherein the shutter control portion sets a period of applying the first hold current and a period of applying the second hold current as periods specified according to type of the material from the hold current condition setting table; and wherein the current adjuster circuit sets the first hold current value and second hold current value as current values specified according to type of the material from the hold current condition setting table.
In addition, according to a sixth aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the fourth aspect, wherein the hold current adjusting means (29, 30) comprises a hold current condition setting table (29) and a current adjuster circuit (30), wherein a hold current value relevant to the motor when the loading starts and a period of applying the hold current and the average current value and a period of applying the average value are stored for each type of the material in the hold current condition setting table, and types of the materials primarily include physical attributes of materials such as the weight, shape, and specific gravity of each material or a total weight of materials to be housed one time in one hopper, the physical attributes being a milestone of a shock during a material drop or a static weight after dropped; wherein the shutter control portion sets a period of applying a hold current to the motor when the loading starts from the hold current condition setting table and a period of applying the average current as periods specified according to type of the material; and wherein the current adjuster circuit sets the hold current value relevant to the motor when the loading starts from the hold current condition setting table and the average current value as current values specified according to type of the material.
In addition, according to a seventh aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the first or second aspect, wherein the shutter control portion (19a) controls a current value of an energizing current supplied to the motor according to a change of a torque required for opening and closing of the shutter during a period for opening and closing operation of the shutter.
In general, a torque required for opening and closing a shutter turnably mounted on a hopper discharge port is not constant during an opening and closing period, and greatly changes.
That is, a large torque is required at the initial state of a shutter opening operation or at the initial stage of a closing operation. When a predetermined period of time has elapsed, the required torque is reduced.
Because of this, at the initial stage of a shutter opening operation requiring a large torque or during a closing operation, it is required to increase an energizing current supplied to a motor. Conversely, when a small torque is applied after the predetermined period of time has elapsed, the energizing current supplied to the motor may be reduced.
Therefore, in the material supply and discharge apparatus configured according to the seventh aspect, a current value of an energizing current supplied to the motor is changed according to a change of a torque required for opening and closing of the shutter, whereby wasteful power consumption can be restrained, and power consumption can be restrained while maintaining excellent shutter characteristics.
In addition, according to an eighth aspect of the present invention, there is provided a material supply and discharge apparatus according to the first or second aspect, wherein the shutter control portion (19a) controls the hold current value so as to be changed according to a change of a torque when the material is charged.
In the material supply and discharge apparatus configured according to the eighth aspect, a hold current value supplied to the motor is changed according to a change of a torque during material charge, whereby wasteful power consumption can be restrained, and power consumption can be restrained while maintaining excellent shutter characteristics.
In addition, according to a ninth aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the first or second aspect, wherein the shutter control portion (19a) comprises:
a motor control portion (20) for outputting a motor drive signal and a hold current control signal based on a hopper release signal from a main control portion (18);
a voltage output circuit (22a) for outputting a current limit signal based on the hold current control signal from the motor control portion; and
a motor driver circuit (21a) for supplying a drive signal based on the motor drive signal from the motor control portion and the current limit signal from the voltage output circuit.
In addition, according to a tenth aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the ninth aspect, wherein, when the hold current control signal from the motor control portion is composed of a first hold current control signal and a second hold current control signal, the voltage output circuit (22a) comprises:
a first transistor (26) that is electrically conductive during a period when the first hold current control signal is inputted from the motor control portion;
first resistance means (25) for, when the first transistor is electrically conductive, providing a first current limit signal;
a second transistor (28) that is electrically conductive during a period when the second hold current control signal is inputted from the motor control portion; and
second resistance means (27) for, when the second transistor is electrically conductive, providing a second current limit signal, wherein the motor driver circuit (21a) changes a current value of the hold current supplied to the motor based on the first and second current limit signal.
In addition, according to an eleventh aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the first or second aspect, wherein the shutter control portion (19a) comprises:
a motor control portion (20) for outputting a motor drive signal, a hold current control signal, and a current adjusting signal based on a hopper release signal from a main control portion (18);
a voltage output circuit (22a) for outputting a current limit signal based on the hold current control signal from the motor control portion;
a motor driver circuit (21a) for supplying a drive signal to the motor based on a motor drive signal from the motor control portion and the current limit signal from the voltage output circuit; and
a current adjuster circuit (30) for adjusting the current limit signal caused by the voltage output circuit based on the current adjusting signal from the motor control portion.
In addition, according to a twelfth aspect of the present invention, in order to achieve the foregoing object, there is provided a material supply and discharge apparatus according to the eleventh aspect, wherein, when the hold current control signal from the motor control portion is composed of a first hold current control signal and a second hold current control signal, the voltage output circuit (22a) comprises:
a first transistor (26) that is electrically conductive during a period when the first hold current control signal is inputted from the motor control portion;
a first variable resistor (25a) for, when the first transistor is electrically conductive, providing a first current limit signal;
a second transistor (28) that is electrically conductive during a period when the second hold current control signal is inputted from the motor control portion; and
a second variable resistor (27a) for, when the second transistor is electrically conductive, providing a second current limit signal, wherein the current adjuster circuit (30) varies the first and second variable resistance based on the current adjusting signal, thereby adjusting the first and second current limit signal, and wherein the motor drive circuit (21a) changes a current value of the hold current supplied to the motor based on the first and second current limit signal.